These parts are helpful for rebuilding early Athearn geared locomotives with a drive system like the one shown here.

Parts from this kit have been used with GP9 and F7 locomotives.

Because they are often broken or are too tight, one of the parts is a replacement for the "cover" that holds the trucks together (Athearn PN 42009). Because these covers remain visible after the shell is installed you'll likely want to print them in black plastic or paint them black. In PLA, these clips are quite fragile, consider them semi-disposable.

Another part facilitates connecting a motor with a 2 mm diameter shaft to the motor coupling (Athearn PN 90105). In my experience these couplings are frequently split (as well as being sized for a larger shaft). An adapter was created rather than replacing the coupling outright in order to retain the superior surface finish of the original's sphere. The center hole is deliberately undersized so it can be drilled out with a 2 mm drill. I used PVA glue to secure the coupling into the printed part and the printed part to the motor shaft.

Three different motor mounts are provided.

The first mount fits (just barely) inside the wider than scale hood of the Athearn GP9 shell. The mount accommodates a strip board to facilitate wiring. The 23.6 mm diameter motor is held in the mount by friction. A dimensioned drawing of the motor is included. Four 2-56 nuts are CA-glued into the inside of the mount so that the original holes in the locomotive frame may be re-used. A layer of elastomer between the frame and the motor mount is intended to reduce noise and vibration. The "washers" from another re-motor kit are placed below the heads of the screws on the underside of the locomotive. Tabs on the top of the mount provide a stable support for the locomotive when it's upside down for service.

Because it hosts a larger, 26.5 mm diameter motor, the second mount will work only with an F7. A second version of the second mount is provided because the diameter of the motor enclosure on the original version is just a little too small, resulting in cracking. If I needed to make a new version of this part, I would print the second version. Both versions are included in case my hypothesis about the cause of the cracking is incorrect. As can be seen in the photos, the shaft of this larger motor is higher than the worm gear shafts. The universal joints included in the original design are relied upon to accommodate this misalignment.

Finally, the kit includes geometry for a replacement spline drive shaft (PN 90106). For robustness, the length of the shaft has been increased by 3 mm. Features on this part are quite small, so it was printed with an 0.2 mm nozzle. Though the surface finish is questionable, the universal joint still operates smoothly.

STEP files of the various parts are available here.

These designs were inspired by the work of Elite194.